Electromagnetic contactor



Dw- 29 1970 H. E. scHLElcHER ,5L ELECTROMGNETIC CONTCTOR 3 Sheets-Sheet Filed Feb` 9, 1968 United States Patent O 3,551,859 ELECTRGMAGNETIC CONTACTOR Harold E. Schleicher, West Hartford, Conn., assignor to Arrow-Hart, Inc., a corporation of Connecticut Filed Feb. 9, 1968, Ser. No. 704,363 Int. Cl. H01h 67/02 U.S. Cl. 335-128 13 4Claims ABSTRACT OF THE DISCLOSURE An electromagnetic switching device made of insulation bodies which fit together in interengaging and interlocking relation, on which are supported fixed contacts, a movable contact carrier electromagnetic solenoid, field piece and armature parts. No metal parts other than screws are used for the mounting or support of the fixed and movable contacts and other parts of the device.

Provision is made on the 'bodies for the attachment and annexation of supplementary poles and/or auxiliary smaller switches by interengagement and interlocking of the casings with formations that are provided on the main device so that when the bodies of the main device are assembled together they hold the supplementary or auxiliary devices.

This invention relates to electromagnetically operated switching devices, commonly referred to as electromagnetic contactors.

In electromagnetic contactors as heretofore known movable contacts have bridged pairs of fixed contacts to open and close the circuits through each line that is connected to the device. These movable contacts were mounted on a carrier which was caused to tmove by energization of a solenoid coil, creating an electromagnetic field to attract the armature against a bias of springs or gravity or both. Such devices have usually been made up of a variety of interconnected links or levers stamped from sheet metal and also including metal rods and pins, the assemibly of which involved a large number of mechanical and manual operations and procedures. Despite careful engineering and design, the parts were subject to bending and twisting, and mechanical wear both in usage and during manufacturing and assembly. 'This caused inaccuracies to develop, not only during the manufacturing but during prolonged -usage of the devices. These inaccuracies limited the usage and the useful life of the devices.

According to the present invention, no metal links or levers or assemblages of stamped sheet metal operating parts are necessary. Except for the current carrying parts, electromagnet, and biasing springs, the device is made wholly of molded insulation components which are formed to be fitted together and to interengage in assembled position, in condition for the fixed parts to be firmly held together in their assembled positions and for the movable parts to respond upon energization of the electromagnet to cause engagement and disengagement of the contacts. Objectives achieved by the invention will be observed as the invention is described herein.

In the embodying of the invention in practical form many new features have ibeen included which are not found in prior contactors.

Modern techniques and materials are used in a unique simple and practical manner.

Linkages and joints involving complicated mechanical operations such as punch-press and power-press fabrications are avoided.

Conversion and alteration of the combination by addition of extra pole units and/ or auxiliary switch units are possible and may be accomplished with great simplicity.

Assembly is simplified to the point of becoming almost a do-it-yourself process, requiring only a few manual operations to put together the individual components and tightening a few screws.

Disassembly is equally simple.

The result of all this is trouble-free life of the device through millions of operations, with wear reduced to almost negligible proportions, and ultimate life beyond any prior device for a similar purpose.

In the drawings:

FIG. l is a side elevation view of an electromagnetically actuated switch or contactor embodying the invention.

FIG. 2 is an end elevation View of the invention looking at the left end of FIG. l.

FIG. 3 is an end elevation view of the invention looking at the right end of FIG. 1.

FIG. 4 is a perspective view of the movable contact actuating assembly used in the invention as illustrated in FIG. 1.

FIG. 5 is a transverse section View taken along line SL-S of FIG. 4.

FIG. 6 is an end elevation view of the movable contact assembly used in the invention as illustrated in FIG. 1.

FIG. 7 is a side elevation View of the movable contact assembly used in the invention as illustrated in FIG. l

FIG. 8 is a plan view of the invention illustrated in FIG. 1 with the cover and electromagnetic body or coil assembly and cover member removed.

FIG. 9 is a plan view of the electromagnetic body or coil assembly of FIG. 8 with the solenoid coil and field piece unit partly broken away.

FIG. 10 is a plan view partly broken away of the solenoid coil and field piece unit alone.

FIG. l1 is an elevation section view of the invention as illustrated in FIGS. l, 2 and 3 with a section taken along the line 11-11 of FIG. 2.

FIG. 12 is a vertical section view along line 12-12 of FIG. 4.

FIG. 13 is a side elevation view of a supplementary pole switch unit, designed for use with the contactor of FIG. 1, and shown assembled on the contactor in FIG. 2.

FIG. 14 is a fragmentary view, partly broken away, showing the mounting of a supplementary pole unit as seen in FIG. 2.

FIG, 15 is a longitudinal mid-section view of the unit of FIG. 13.

FIG. 16 is a side elevation view of a supplementary push button type of switch unit designed for use with the contactor of FIG. 1, and shown assembled on the contactor in FIG. 2.

FIG. 17 is a fragmentary view, partly broken away, showing the mounting of a supplementary switch unit which is shown in mounted position in FIG. 2.

FIG. 18 is a side elevation view of the supplementary push-button type switch unit of FIG. 16, `but of the other side.

FIG. 19 is a longitudinal section View transversely through the unit of FIG. 17 and FIG. 18 with the section being along line 19-19 of FIG. 18.

The invention as illustrated in the drawings is made up of several interconnected assemblies each having a number of parts.

The assemblies are mounted on a base 10 made of molded insulating material. These assemblies are:

(l) A base assembly comprising an insulation base member on which are mounted xed contacts and terminal mem-bers.

(2) A movable contact assembly which is mounted in the base and includes an insulation contact carrieron which is mounted a plurality of bridging contacts each adapted to engage and disengage a pair of fixed contacts.

(3) An actuating assembly for moving the movable contact carrier including a pivoted U-shaped bell-crank lever member carrying an electromagnet armature.

(4) A field assembly for an electromagnet including an insulating body on which is mounted a sub-assembly consisting of a solenoid coil embedded in insulation and a laminated U-shaped field piece passing through the coil.

(5) A cover made of insulation for the electromagnet field assembly mounted on the same.

In addition, supplemental switching assemblies or units may be annexed or attached to the assembled combination of the assemblies described above.

One such supplemental assembly or unit may be an extra pole unit comprising an insulating body having a pair of fixed contacts and a movable bridging contact, and an actuating member positioned to be moved by the actuating assembly when the electromagnetic operating means is energized.

Another supplementary assembly or unit may be a push button actuated switch having a pair or pairs of normally open or a pair or pairs of normally closed contact sets or combinations thereof in which a bridging contact or contacts are moved into engagement with a pair of fixed contacts or out of engagement with a pair of fixed contacts, or both, by and simultaneously with attraction and release of the armature.

The assemblies comprising the ybasic combination may be so formed and configured with tongue and groove or dovetail formations as to enable attachment, without screws or the like, of the supplementary units and to hold them in such position of interengagement with the basic units of the combination that, after the securing screws which secure the main component assemblies together are screwed tight, the supplemental unit or units are firmly attached.

THE BASE MEMBER Referring more particularly to the individual components or assemblies, the base is a molded insulating body of a generally rectangular shape and is hollowed out with three parallel similar cavities for the reception of pairs of aligned fixed contact and terminal members 12a and 12b which are stamped from sheet metal into what might be called a lazy-Z or double oblique angled shape, as viewed in FIG. 1l.

On one end of each member (the inner end as viewed in FIG. ll) is a contact button such as 12C, while the other end extends toward the outside and has a terminal screw 12t threaded through it.

The fixed contacts may be secured to the base by screws 12s threaded into eyelets imbedded in the base 10 or by any other conventional means.

On each of the opposite sides of the base that are parallel to the contacts, two parallel spaced ribs 14a, 14b, and 15a, 15b, are formed with their parallel edges undercut or dovetailed (see FIGS. l, 2, 8 and 17 for the dovetailing). These dovetail ribs provide means to secure additional units to the sides of the base, as will subsequently more fully appear.

MOVABLE CONTACT ASSEMBLY The movable contact assembly consists of an elongated molded insulation carrier 20, as illustrated in FIGS. 1, 6 and 7. The carrier can be dropped into the open upper face of the base 10 during assembly (as has been done in FIG. 8) over the fixed contacts, the base cavities and their walls being molded to receive and guide the carrier in movement toward and from the fixed contacts. The central portion of the carrier has three identical depending cage-like formations 21, 22, 23 spaced apart. Generally speaking, they are angularly U-shaped formations depending by their arms (e.g. 21a, 21e) from the central portion of the carrier, in side by side spaced relation, as

illustrated in FIG. 7. The bottom of the U, e.g. 2lb, in each instance serves as a saddle onto which is pressed a bridging contact e.g. 24, which is stamped from sheet metal into fiattened U shape, as seen in FIG. 6 with the ends thereof upwardly inclined at opposite oblique angles from the central portion that rests on the saddle.

Pressing against each end of the bridging contact are the coil compression springs 25, Z5, the other (upper) ends of the springs pressing against lateral extensions 26 from the carrier 20, there being three extensions on each side of the carrier, with the three on one side being opposite the three on the other, as may be observed in FIGS. 6, 8 and l1.

For moving the contact carrier there is an endwise extension 28 from each end thereof, embraced by the forked ends of the arm 31 of an armature assembly 30, as hereinafter described.

To bias the Contact carrier 20 and the armature assembly, spring pressed plungers 27 (see FIG. l) are mounted in two symmetrically located wells, one in each of the walls of the base beneath each end of the contact carrier. Each of these plungers is pressed upwardly against the bottom tyne of the forked end of the arms 31 of the armature assembly 30, as in FIGS. l and 1l, by a coiled compression spring 29 seated in the well and received in the hollow head of its plunger 27.

ELECTROMAGNETIC CONTACT-ACTUATING MEANS This means consists of two assemblies: (l) an electromagnet field assembly consisting of (a) a supporting member or body 40 and (b) a solenoid coil and field piece; and (2) an armature assembly, as will become apparent as these assemblies are described. They may `be assembled with the greatest of ease on the base 10 as individual self-contained units; and equally they may be disassembled from the base.

(1) The field assembly (a) The supporting member.-This consists of an insulating support member or body 40 formed from molded insulation material into the form best observed in FIGS. 9 and 1. FIG. 9 shows the assembly when removed from the contactor, looking at the top or outer face. The body is of irregular shape but symmetrical about its longitudinal center line. Viewed from the side (as in FIG. l) it has generally rectangular sides with generally triangular plate-like extensions 42 at the end of each of its sides. The extensions taper to tips 42 which when the body 40 is assembled upon tha base end extend under overhanging projections 18 which'extend up from the base at two opposite corners thereof. The width of the body 40 approximates that of the base; and the surfaces of the bottom body lie in a plane and on the top surface of the base 10. The body 40 is located in proper position on top of the `base by conical collars 19 extending up around screw bolt passages through the base from the top surface of the base at those corners of the base which are opposite to the tips 42. These conical collars are in register with and are received in conical recesses in the bottom of the body 40 when the body 40 is placed upon the base. Then screw bolts may be inserted through the registering holes in the body 40 and through the collars to secure the base 10 and body 40 together.

Referring to FIG. ll, on the inside of each of the projections 18 on the body 40 there is a vertical wall closing the inner side of the overhang. This prevents sidewise movement of the tips 42 when they are engaged under the overhang.

The bottom of the body 40 overlies the trunnion recesses 16 in the base 10 and the trunnions 32 of the hereinafter described armature assembly holding the trunnions in the recesses.

(b) The solenoid coil and field meca-This structure is designated as a whole by numeral 50. A solenoid coil is embedded and completely encased in a casing 51 of molded insulating material, as illustrated in FIG. 10, with a shelf S2 of insulating material extending from one side and preferably molded integrally with the casing. The coil is, or may be, in two identical torroidal units 53, 54 that are connected electrically in series. The shelf S2 has four compartments in which are mounted four stamped sheet metal and screw type wire terminals 55 that are separated by parallel compartment walls S6. The ends of each coil are connected to the first and second terminals and to the third and fourth terminals, respectively, before molding; and the two inner terminals (second and third) may be bridged by a connector 57 after molding, if circumstances indicate that such connection should 'be made.

The coil-encasing housing is molded with two parallel passageways through the axes of the coils for reception of a laminated U-shaped eld piece 58, the back face of the transverse portion thereof being iiat.

To cushion the iield piece against the shock of the armature striking against it, as hereinafter described, a slot is molded in the held-supporting body 40, located behind the at rear face of the field piece, running along the whole length f said rear face and beyond. In this slot a ripple-type leaf-spring 59 is placed edgewise so that its undulating opposite surfaces will press against the surface of the slot and against the rear facing of the field piece, at a plurality of points symmetrically.

Thus, the field components of the electromagnet, when assembled, form a complete unit 50 which may be handled and assembled upon the body 40 as a single component. To facilitate such assembling, and to maintain the iield assembly 50 in position on the body 40, the body is molded with a cavity in its mid-portion, as may be observed in FIGS. 9 and ll.

To hold the eld unit 50 on the body 40 a shallow flat-topped cover 60 of molded insulation material is secured over the field units by bolts 61 which pass downwardly through holes in the cover into the body 40 near neighboring corners. The cover is hollowed in its under surface to receive in close-fitting embrace the upper part of the coil casing 51, as may be seen in FIG. 1l.

(2) The actuating assembly To actuate the movable contact carrier, a bell crank type electromagnet armature assembly 30 (see FIGS. 4, 5 and 11, particularly) is mounted in the base 10 pivotally in open V-shape recesses 16 that are provided in the side walls of the base in opposite aligned positions (FIGS. 1 and 8).

The body of the assembly is made of molded insulation and, as may be seen best in the perspective View of FIG. 4, is generally speaking of U-shape, with its arms formed identically in the shape of parallel bell-crank levers 31. Trunnions 32 extend from the outer side surfaces of the arms 31, for seating in the V-recesses 16 in the sides of the base. The ends of the arms 31 are forked to embrace the extending ends 28 of the contact carrier, as previously mentioned, to cause the carrier and bridging contacts 24 to move toward and away from the xed contacts 121C. The armature assembly is biased toward inactive position as shown in lFIGS. 1 and 11, by the springpressed plungers 27 pressing against the bottom side of the forked ends of the arms 31 in those figures, all as previously mentioned.

The transverse part 33 of the armature assembly has a rectangular opening through it and extending longitudinally along it. The opening is longer at its rear than at its front, providing shoulders 35 at each end. (See FIG. 12). These shoulders have radial surfaces, as shown in FIGS. 5 and l1 (in dotted lines), to permit the armature assembly to align with the magnet pole faces by limited rocking movement. In the opening is inserted a rectangular laminated bar armature 36 ywith raised machined faces 36 on its front adjacent each end, to engage the ends of the eld piece. The armature laminations are otherwise CII of substantially the same conguration as the opening (Viewing its section in FIG. 12 wherein is seen one lamination) so that the shoulders 36s on it (see FIG.12) will rest on the shoulders 35 of the opening to hold the armature bar in place. A back plate 39 of insulating material is secured by screws 38 to the body 33. Between the back plate and armature bar a cushioning pad 37a of rubber or other suitable shock-absorbing resilient material may be placed; and similar cushioning ads 37b may be placed between the upper and lower aces of the bar and the adjacent boundaries of the opening in the transverse part 33 of the body.

The cushioning of the armature bar 36 and the resilient support of the field piece 58 to absorb shocks, also enables the armature and field piece to align themselves for optimum engagement and magnetic circuitry.

The subject matter of the cushioning and mounting of the armature is claimed in a divisional application tiled June 17, 1970, Ser. No. 46,845.

To cushion and dampen the opening movement of the armature assembly 30 as it drops open under urge of the biasing springs 29, two damping fingers 19 made of molded synthetic plastic material in tapered thin strip form are placed in slots in the base 10 (see FIGS. 1 and 2) in position to be engaged by opposite sides of the armature assembly.

For the purposes of actuating auxiliary or supplementary units which may sometimes be attached to the contactor, two lugs 34 may be formed on the armature assembly on opposite sides, one extending from each side of the molded bell crank member to engage a cooperating stud on the auxiliary switch as will subsequently be described.

SUPPLEMENTARY UNITS On some occasions and for some usages it may be desirable or necessary to have the energization of the electromagnet cause actuation of one or more additional units by closing movement of the armature assembly.

These supplementary units may be either an extra pole like one of the three poles above described and illustrated in FIGS. 13, 15 having contacts capable of handling current and voltage requirements equal to Ithose of said three poles; or the unit may be an auxiliary switch having normally open and/or normaly closed switch contacts or combinations thereof for one or more auxiliary or supplementary circuits as indicated in FIGS. 16, 19 or both another pole and an additional switching unit may be wanted.

To enable these supplementary units to be attached to or annexed to the contactor without separate screws or similar securing means, the base body and cover members 10, 40 and 60, respectively, are formed exteriorly to cooperate and engage with exterior formations on the casings of the units, for mutual interengagement and interlocking when the components or assemblies of the contactor are fitted and secured together. The manner and means for accomplishing this will appear from the following description:

(a) Extra pole addz'tons.-Re'ferring to FIGS. 13-15, the supplementary unit comprises a molded insulation casing having substantially plane side walls in which are parallel channels 71, the parallel edges of which are undercut at an acute angle forming the channel into dove formation as viewed in transverse section (see FIG. 14). The casing is molded -with a cavity for reception, mounting and movement of the switch elements as hereinafter described. A cover 73 iits over and covers the open top of the casing. The channels are dimensioned and positioned to receive snugly the dovetail ribs 14a, 1411 on the base member 10 as the unit 70 is placed against the side of the base 10 above the ribs and is slid down with the channels 71 in register with the ribs.

The channels and ribs are so dimensioned and positioned that when the unit 70 is connected to the base 10 with the unit slid on the ribs as far as possible the top of the unit be flush with the top of base 10. In order to hold the unit 70 in that position the side wall of the eld supporting body 40 overhangs the cover 73 of the unit 70 at least as much as the ribs protrude from base 10. Thus, while the body 40 remains secured on the base 10 the unit 70 cannot be removed and no other means is required to hold the unit in that assembled position.

The switching contacts are within .the casing 70 and may be of various different forms, sizes and capacities, but when the unit is to be usable as a fourth pole it is preferable that the contact carrier 76 support backing springs 75 pressing against bridging contact 74 for engagement with fixed contact buttons 72e on terminal members 72 secured to the casing 70 by screw bolts 72s all of like form and in a like manner to equivalent parts in the contactor itself. The carrier 76 however need only be onethird the length of carrier 20.

To enable the contact carrier 76 to be actuated by and simultaneously with the carrier a pair of parallel spaced lugs 78 extend one above the other from the carrier 76 through a wide slot in the easing 70 toward the base 10 in position to overlie and underlie and to be in constant engagement with the extension 128 from the carrier 20. The location of the extension 28 is shown in dotted lines in FIG. 15. Hence the bridging contact 74 of the added pole is actuated at the same time and partakes the some movement as the bridging contacts 26 inside the contactor.

(b) Auxiliary switch addton.-Referring to FIGS. l6-19, an auxiliary switch has its switching parts housed within a molded insulation easing (designated generally by numeral 80) having a hollow ibase part 81 covered over by a cover part 82 to hold the switching parts in properly assembled position therein. The casing may be of any desired shape, the shape shown in FIGS. 16 and 18 illustrating only one convenient form. The cover part 82 is flat, while the base part is recessed in various places to receive the several switch parts and wire connection terminals.

For mounting the switch on the contactor, a wide rectangular flat plate-like rib 83 is molded integrally with the base part 81. Its longer edges are undercut or dovetailed as at 83e, toward the surface of the base part, as may be seen in FIG. 19. These dovetailed edges 83e are adapted to t in opposite parallel undercut dovetailed edges 82e of a recess 82R in the side wall of the body 40, as may be seen in FIG. 9.

The recess 82R is, generally speaking, of the same size and shape as the wide rib 83, so that the rib 83 may be fitted in the top end of recess 82R with its bevelled edges in dovetail engagement therewith. Thus the rib will slide into the recess as the auxiliary switch is pressed toward the base 10 of the contactor.

One or more auxiliary switches 80 may thus be attached or annexed to and flush against the side walls of the body 40 without the use of screws, rivets or like fasteners. To make that annexation and attachment the cover 60 is removed while the rib 83 is inserted in and slid along the recess 82R. The cover 60 is then placed on the body 40 with the cover engaging the top edge of the rib 83. When the cover is secured on the body 40 by bolts 61 the auxiliary switch will be rmly and permanently secured to the body 4t] of the contactor.

The interior parts of the switch 80 may be varied to suit varying demands and requirements. One particularly useful form includes a bar 84 of insulation material extending lengthwise centrally of the casing in a channel 81s in the base part 81.

Mounted slidably on the bar 84 within passages through it at opposite ends are spaced bridging contact bars 85, 85' which extend through the passages and are adapted to bridge and to disengage pairs of fixed contacts 86 and 86 as the bar is moved axially to and fro. The xed contacts are mounted on the cover part 82 of the switch casing. A coiled compression spring 87, 87' positioned 8 within each passage presses against each bridging contact to resiliently mount it.

To bias the contact carrying bar 84 a coiled compression spring 88 is mounted Linder it (as viewed in FIG. 19) pressing at one end against the base part 81 of the casing and at its other end against a lateral projection from th: bar 84.

In order to actuate the auxiliary switch as the contactor operates, a stud 89 extends laterally from the bar through a longitudinally extending slot 81s in the end ot' the base part. The stud extends toward the contactor into the path of the lug 34 on the armature assembly.

Thus, as the electromagnet is energized and the armature assembly is actuated, the auxiliary switch will be operated when the lug 34 of the armature assembly engages the stud 89 on the movable contact carrying bar 84.

The subject matter of the supplementary units and their attachment and cooperation with the main switching device is claimed in a divisional application tiled J une 17, 1970, Ser. No. 47,082.

A particular advantage of the use of plastic with its resilient weight reduction on moving parts which must be driven by the magnet is the ability to use dual voltage, wide range, wide frequency coils. For example, coils rated at 208-240 volts at 50/6() cycles and 440-480 volts at /60 cycles.

Such coils provided with multiple leads enable the user to utilize any voltage or frequency within the described range.

The magnet of the present invention requires less power to achieve the desired results.

In addition, the cushioning means above described extends the mechanical life of the mechanism because it softens the blow of the moving armature seating in attracted position. In designing coils for wide range voltage and frequency, the coils have to be made stronger and heavier. In the past, this made the magnet beat itself to death when used on voltage at the higher end of the range.

The foregoing also provides a commercial advantage, in that fewer devices need to be stocked because of the utility of one coil for several voltages and frequencies.

Many modifications within the scope of the invention will occur to those skilled in the art. Therefore the invention is not limited to the specific embodiment illustrated and described.

I claim:

1. An electromagnetic switching device comprising insulation base means, xed contact means mounted within said base, movable contact supporting means slidably mounted within said base, movable contact means on said supporting means, pivotable operating means made of insulating material engaging said supporting means for moving said movable contacts, pivot means formed integrally with said operating means, open bearing means formed on said base means to provide a pivotal support for said operating means when assembled, an electromagnetic armature secured on said operating means and mountable as a unit therewith, electromagnetic field creating and concentrating means, means made of insulation for supporting said field means, and means securing said base means and said eld supporting means together and holding said operating means in said pivotal support.

2. An electromagnetic switching device as claimed in claim 1 in which the operating means comprises a molded insulation bell crank lever of U-shape having a transverse portion, and an armature mounted on said transverse portion.

3. An electromagnetic switching device as claimed in claim 2 in which said transverse portion has an aperture in which said armature 1s seated, and means to hold said armature in said aperture.

4. An electromagnetic switching device as claimed in claim 2 having a recess in said transverse portion with an arcuate surface engaged by said armature to permit alignment of the armature with the lield means by limited rocking motion.

5. An electromagnetic switching device as claimed in claim 1 wherein said operating means is formed with an aperture having shoulder means against which said armature rests, and a member secured over said aperture and an armature holding the latter in the former.

6. An electromagnetic switching device as claimed in claim 1 wherein said field means includes solenoid coil means encased unitarily in molded insulation case with passageways through it axially of said coil means, and a magnetic eld piece having legs extending through said passageways.

7. An electromagnetic switching device as claimed in claim 5 having resilient cushioning means mounted in said aperture to absorb the shock of said armature striking against said field piece.

8. An electromagnetic switching device as claimed in claim 6 having cushioning means comprising a leaf spring engaging said eld piece which exes as said field piece is struck Vby the armature.

9. An electromagnetic switching device as claimed in claim 7 wherein said field means includes solenoid coil means encased unitarily in a molded insulation case with passageways through it axially of said coil means, and a magnetic field piece having legs extending through said passageways and iixedly mounted resilient cushioning means engaging said eld piece to absorb the shock of said armature striking against said tield piece and said cushioning means serving also to assist the mating of the armature and eld piece.

10. An electromagnetic switching device as claimed in claim 1 wherein the I'ield supporting means comprises an insulating body seated on said base means, and means Securing said body to said base means; and wherein said eld piece having legs extending through said passageways, 40

said field means being mountable as a unit on said body; and cover means over said field means secured to said body holding said eld means in assembled position on said body.

11. An electromagnetic switching device as claimed in claim 10 in which the operating means comprises a molded insulation bell crank lever of U-shape having a transverse portion, and an armature mounted on said transverse portion.

12. An electromagnetic switching device as claimed in claim 11 in which the transverse part of the Abell crank lever has an aperture in which said armature is seated, and means to hold said armature in said aperture.

13. A device as claimed in claim 2 in which the movable contact supporting means has extensions which are elliptical in cross section, and said bell crank lever has forked arms embracing said elliptical extensions.

References Cited UNITED STATES PATENTS 3,354,415 11/1967 Gribble et al. 335-132(X) 3,319,199 5/1967 Bauer 335-128 3,309,577 3/1967 Roll, Jr. 317-99 3,264,526 8/1966 Wiggerman 317-101 3,243,545 3/1966 Platz et al. 335-132 3,226,516 12/1965 Kussy et al 335-132(X) 3,202,244 8/1965 Vogelsong et al. 335-2770() 2,969,444 1/1961 Deissler 335-128 1,424,809 8/1922 Donle 200-172(UX) OTHER REFERENCES Motor Control, by I-T-E (Bulletin MG-IA) pp. 4-5 & 7, Dec. 16, 1963.

BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner Us. c1. XR. 335-13; 

